Pumping apparatus



Oct. 6, 1931. A. E. G ULL PUMPING APPARATUS Filed June 22. 1928 a. @la o ,6%

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Patented 6, 193i UNITED STATES PATENT OFFICE n Anonr rzwALn GULL, or LONDON, ENGLAND PUNHNG Arrm'rus Application med .Tune 22, 1928, Serial No. 287,558, and in Great Britain J'uly 26, 1927.

This invention relates to pumping apparatus and has reference to apparatus designed to ensure a constant rate of delivery of liquid irrespective of variations in resistance to The invention comprises pump regulating apparatus particularly applicable to the manufacture of artificial silk from cellulose acetate or other cellulose derivatives, as in such manufacture it is important, in order to ensure constant and regular denier, that the delivery of the solution through the filament forming jets or orifices shall remain constant in spite of the variations in resistance to iiow which arise as a consequence of the Working of the apparatus.

One method of accomplishing this which has been proposed is to provide two pumps in series so arranged and proportioned that one pump delivers to the other pump at a greater rate than the other pump delivers, the excess from the first pump escaping through a valve controlled automatically in accordance with the pressures in the delivery conduits of both l the pump elements.

Another methodwhich has been adopted is to provide a pump and to introduce into the system an artiiicial resistance to flow such as a capillary valve capable of adjustment by hand in order to compensate any variations in the resistance against which the system has to work.

In such apparatus, when applied to the extrusion of artificial laments, which is usually designed to deliver minute quantities regularly at high pressures, the leakage, which is unavoidable in mechanical apparatus, becomes the determining factor in the regularity of the discharge, and it is therefore essential that the regulation should be governed by the variations in leakage which are a function of the pressure variations.

In the first method referred to above, leakage is altogether avoided by the fact that the second of the two pumps is balanced as regards pressures, that is to say, both suction and discharge are always under the same pressure, no matter how its magnitude may alter, and therefore leakage does not occur.

In the present invention, means are provided whereby the same result is obtained although leakage may occur, butthis leakage would be always constant, no matter how the external pressure may vary, owing to the fact that the pump is always working against a constant pressure.

The present invention consists of pump regulating apparatus having two pumps in series, wherein means are provided whereby resistance in the delivery of the second pump controls automatically the delivery-of the lirstpump, or the invention may be consideredV to comprise pump regulating apparatus for overcoming a variable resistance, provided in the delivery of a pump which automatically keeps the discharge pressure of thatpump constant and higher than the varying resistance which has to be overcome.

The capillary valve may be provided with a servo-motor or operating piston movable freely 1n a cylinder and of which one side is subJected to the pressure at the suction side and the other to the pressure of the delivery side of the first pump. v

The capillary valve is preferably of the screw thread or helical groove type the thread or groove being formed on a spindle moving freely in a cylinder and having an inlet from the second pump opening into the cylinder between the ends of thev screw thread or helical groove.

The accompanying drawing illustrates diagrammatically a sectional view of the apparatus for one method of .carrying out the invention as applied to the manufacture of artilicial iilaments.

In this drawing 2 and 3 are'the two pumps arranged in series. These pumps are of the rotary type driven by gear wheels 2a and 3a respectively, the gear wheels being driven from a gear wheel 4 mounted on a power shaft 5. This gearing may be arranged to drive the pumps at the same or different speeds.

The pump 2 delivers a constant quantity of liquid through the delivery outlet 2b which is continuous with the suction 3b of the pump 3, and the pump 3 delivers this constant amount of liquid at a definite pressure through a capillary valve 6, which consists of a screw thread on a spindle 6a moving freely in a cylinder 6b. The liquid delivered t rough the valve 6 passes through a continuation of the cylinder 6b and a filter 6c to a jet head 6d, which jet head 6d may be such as is used in the manufacture of artificial silk filaments. The pump 3 delivers liquid through an outlet 3c which opens into the cylinder 6b at a point between the ends of the screw thread of the valve 6, and on the plain upper portion of the spindle 6a is provided a piston 6e which floats or moves freely in an enlarged section Gf of the cylinder 6b. The spindle is provided with a central passage 6g which places the space between the top of t e valve spindle 6a and the closed end 6h of the cylinder in communication with the space between the lower end of the valve 6 and the filter 60.

A. delivery passage 2c places the delivery outlet 2b in communication with the space below the piston 6e in the cylinder f, while the upper side of the piston 6e is incommunication with a suction inlet 2d to the pump 2 by means of a passage 2e. The passage 2e extends from a branch pipe 2f in which is provided a non-return valve 2g and which at its lower end is in communication with a pipe 2h connected to the liquid supply. Between the passages 2e and 2c is rovided a bye-pass passage 2i provided with an adjusting valve 2y', which is necessary as the pump 3 having in such apparatus to work against a high pressure it therefore has a certain constant leakage, i. e. it cannot absorb the whole output of the pump 2 which being balanced has no leakage. The result of such leakage would be to cause hunting and a constant opening and closing of the non-return valve 2g. The fine adjustment needle valve 2 7' allows this small quantity of leakage to be bye-passed to the suction of the pump 2 and thus prevents hunting. The valve 2j also allows of the setting of the iston 6e to any desired position.

T e capillary valve 6 operates to place in the delivery of the second pump 3 a frictional resistance varying in amount in accordance with the length of thread of the valve 6 in an extension of the cylinder 6b below the delivery outlet 3c, and this resistance together with the resistance of the jet head 6d, and that of the filter 6c represents th discharge pressure of the second pump 3.

The capillary valve 6 is adjustable in its housing and adjustment is automatically provided for by the floating piston 6e being mechanically connected to it and arranged in the cylinder Gf in the circuit of the first pump 2, the two ends of' which cylinder on either side of the piston 6e being connected with the suction and d1s charge branches 2e and 2c of the first pump 2 respectively.

From the above construction it will be readily understood that if the external resistance increases, the increased pressure will react through the second pump 3 into its suction pipe 3b and this causes the floating piston 6e to move in such a way that it will shorten the effective length of the capillary valve 6 and thus reduce the frictional resistance. The fluid displaced by the floating piston 6e in its movement will be forced into the suction passage 2e of the first pump 2, thus closing the non-return valve 2g and keeping the, pressures on both sides of the pump 2-which functions as a metering pumpequah The piston 6e will continue to move until equilibrium of pressures is again established on the discharge side, when the non-return valve 2g will open again and .more fluid will enter the first pump 2.

It will thus be seen that I have by my invention provided a method of and means for pumping which will ensure a constant delivery of liquid irrespectively of variations in the external pressure against which the delivery has to be effected and consequently by means of this arrangement artificial silk filaments of constant denier can be manufactured with certainty.

What I claim and desire to secure by Letters Patent is 1. Pump regulating apparatus having two pumps in series, wherein 1s provided a capillary delivery valve operating piston movable freely in a cylinder and of which one side is tsubjected to the pressure at the suction side and the other to the pressure 'of the delivery side of the first pump.

2. Pump regulating ap two mechanically couple pumps connecte in series, a delivery outlet from the second pump of the series, a cylinder, a floating piston, a variable resistance to flow from the pump, the cylinder being connected at one end to the suction side of the first pump and at the other end to the delivery side of the said pump, the piston moving freely in the said cylinder and mechanically connected to the variable resistance which moves freely in the delivery outlet of the second pump.

3. Pump regulating ap aratus comprising two mechanically couple pumps connected in series, a delivery outlet from the second pump of the series, a cylinder, piston, a regulatable bye-pass, a variable resistance to flow from the um the cylinder being connected at one en to t e suction side of the first pump and at the other end to the delivery side of the said pump, the piston moving freely in the said cylinder and mechanically connected to the variable resistance which moves freely in the delivery outlet of the second pump, and the said regulatable bye-pass being connected at one end to aratus comprising i.

a floating one end of the cylinder and at the other end to the other end of the cylinder.

4. Pump regulating apparatus comprising a delivery outlet from the pump, a slidable cylindrical member having on its periphery a helical fluid conveying groove extending to its end, the helically grooved cylindrical member being adapted to fit in and move axially in the said delivery outlet and to form a controlling portion of the regulating apparatus.

5. Pump regulating apparatus comprising two mechanically coupled pumps connected in series, a delivery outlet from the second pump of the series, a cylinder, a floating ston, an axially slidable cylindrical member having on its periphery a helical fluid conveying groove extending to its end, the cylinder being connected at one end to the suction side of the first pump and at the other end to the delivery side of the said pump, the piston being adapted to move freely in said cylinder and being mechanically connected to the helically grooved cylindrical member which is arranged to move freely in the delivery outlet of the second pump.

6. Pump regulating apparatus comprising two mechanically coupled pumps connected in series, a delivery outlet from the second pump of the series a cylinder, a lioating piston, a regulatable bye-pass, an axially cylindrical member having on its periphery a helical iiuid conveying groove extending to its end, the cylinder being connected at one end to the suction side of the first pump and at the other end to the delivery side of the said umptl 1e piston being adapted to move free y in said cylinderand being mechanically connected to the helically grooved cylindrlcal member which is arran ed to move freely in the delivery outlet o the second pump, and the said regulatable bye-pass being connected at one end to one end of the cylinder and at the other end to the other end of the cylinder.

7. Pump regulating apparatus comprising two mechanically coupled pumps connected in series, suction and delivery passages for the pumps, a cylinder, a iioatmg piston, a slidable cylindrical member having on its periphery a helical fluid conveying groove extending to its end, the outlet for the dehvery of the second pump being continuous with and coaxial with the cylinder and contaimng the helically grooved member, the cylinder containing the floating piston and being connect,- ed above the piston to a assage communicating with the suction of t e first pump and below the piston to a passage communicating with the delivery of the first pump and the suction of the second pump, t e delivery of the second pump opening laterally into the outlet through an opening across which extends the helically grooved portion of the cylindrical member which is connected coaxially with the floating piston.

8. Pump regulating apparatus comprising two mechanically coupled pumps connected 1n series', suction and dehvery passages for the pumps, a non-return valve, a cylinder havmg a closed upper end, a floating piston, a slidable cylindrical member havlng on its periphery a helical iiuid conveying groove extendlng to' its end, the outlet for the delivery of the second pump being continuous with and coaxial with the cylinder and conta1ning the helically grooved member, the cylinder containing the iioating piston and be'- ing connected above the piston to a passage communicating with the suction of the rst pump and the non-return valve, and below the piston to a passage communicating with the delivery of the first pump and the suction of the second pump, the delivery of the second pump opening laterally into the outlet through an opening across which extends the helically grooved portion of the cylindrical member lwhich is connected by a piston-rod coaxially with the floating piston, an axial hole being provided through the helically grooved cylindrical member, the piston rod and the piston.

9. Pump regulating apparatus comprising a delivery outlet leading from the pump, a cylinder leading to the said outlet, a spindle sliding in said cylinder, extending into the outlet, and having a grooved passage formed on the exterior thereof, the grooved portion of the spindle extending into the outlet and being automatically movable therein to vary the length of the groove in operation.

In witness whereof I aiiix my signature.

v ADOLF EWALD GULL. 

